Liquid distributor for feeding liquid to a rotating atomizer

ABSTRACT

A liquid distributor for feeding liquid to a rotating cup-shaped atomizer wheel, in the sidewall of which a plurality of ejection apertures of ducts are provided uniformly distributed along the circumference. The distributor consists of a body mounted coaxially with the atomizer wheel, said body being provided with a number of helical ducts, the helical axis of which coincide with the axis of the atomizer wheel and terminate in an annular conduit which is coaxial with the atomizer wheel and terminates with an ejecting edge inside the wheel. The helical ducts impart a rotating motion in direction of atomizer wheel rotation to the liquid which is finally flung out from the ejecting edge against the sidewall of the cup-shaped wheel.

United States Patent [19] Masters et a1.

[ LIQUID DISTRIBUTOR FOR FEEDING LIQUID TO A ROTATING ATOMIZER [75]Inventors: Keith Masters, Skovlunde; Orla 1 Straarup, Birkerod, both ofDenmark [73] Assignee: Aktieselskabet Niro Atomizer, Gladsaxevej,Soborg, Denmark [22] Filed: May 10, 1971 [21] Appl.No.: 141,560

[51] ..B05b 3/02, F23d 11/04 [58] Field of Search ..239/222, 214

[56] References Cited UNITED STATES PATENTS Pilo et al. .239/222 I [451Feb. 3,1973

3,103,311 9/1963 Kempf ..239/222 X 3,250,473 5/1966 Hege ..239/2222,920,830 1/1960 Ngrop et al ..239/222 Primary Exzimz'ner- Lloyd L. KingAttorneySughrue, Rothwell, Mion, Zinn & Macpeak ABSTRACT A liquiddistributor for feeding liquid to a rotating cup-shaped atomizer wheel,in the sidewall of which a plurality of ejection apertures of ducts areprovided uniformly distributed along the circumference. The distributorconsists of a body mounted coaxially with the atomizer wheel, said bodybeing provided with a number of helical ducts, the helical axis of whichcoincide with the axis of the atomizer wheel and terminate in an annularconduit which is coaxial with the atomizer wheel and terminates with anejecting edge inside the wheel. The helical ducts impart a rotatingmotion in direction of atomizer wheel rotation to the liquid which isfinally flung out from the ejecting edge against the sidewall of thecup-shaped wheel.

5 Claims, 6 Drawing Figures PATENTEUFEBIEHHB I 3.716.193

' sumaora FIG. 2

PATENTEUFEB 13 ms 13.716 193 SHEET 30F 4 FIG. 3

PATENTEDFEH 13 m5 3.716.193

'SHEET u 0F 4 FIG. 4

LIQUID DISTRIBUTOR FOR FEEDING LIQUID TO A ROTATING ATOMIZER Thisinvention relates to a liquid distributor for feeding liquid to arotating atomizer wheel of the type which consists of a cup-shapedwheel, in the side wall of which a plurality of ejection apertures orducts are provided uniformly distributed along the circumference, inaddition to which the liquid distributor is adapted to impart a rotatingmotion to the liquid in the direction of atomizer wheel rotation.

The known liquid distributors which are adapted to impart a rotatingmotion to the liquid while this is being fed to the atomizer wheel, areemployed in connection with atomizer wheels of the type shaped like arather flat plate and from which the liquid is hurled out over the edge.In this case, the purpose of imparting a rotating motion to the liquidis to obtain a uniform distribution of the liquid over the entire wheelsurface so that the film of liquid along the whole circumference is,essentially, of the same thickness.

With atomizer wheels having ejection apertures or ducts fitted along thecircumference of the wheel and which consequently are shaped like a deepdish, a nonrotating supply of liquid is normally used on account of itbeing possible to operate with a larger volume of liquid in the bottomof the cup-shaped wheel, from where the liquid is forced out against theside wall and up along same and out via the ducts by means of thecentrifugal force, whereby there normally exists no risk of anon-uniform distribution in the ejection ducts taking place.

However, when working with atomizer wheels of the type dealt with ofrelatively small diameter, and in particular when using suspensions witha very high solid matter content, difficulties do arise in achieving asatisfactory distribution and it is impossible to obviate thesedifficulties by utilizing a rotating motion of the liquid suppliedproduced by the known methods where a feed pipe has been mountedcoaxially with the wheel and with a tangential supply of the liquid atthe topmost end of this pipe so that the liquid is distributed along theinternal surface of the pipe and hurled from its lower edge in the formof a conical film of liquid striking the bottom of the wheel.

In order to solve the problems discussed, the distributor according tothe invention is constructed in such a way that it consists of a bodyhaving a plurality of helical ducts mounted coaxially with the atomizerwheel, the helical axis of which coincide with the axis of the atomizerwheel and terminate in an. annular conduit that is coaxial with theatomizer wheel and terminates with an ejecting edge inside said wheel.

It has been proven that it is possible to achieve by means of thisconstruction that the liquid is ejected from the distributor in the formof a fairly thin film having a very flat conical shape striking the sidewall of the wheel in which ejection apertures or ducts have beenprovided. and that a particularly uniform distribution is achievedhereby.

At the same time, it is achieved that the bottom of the wheel is notsubjected to wear and tear and,

moreover, the splashing and spattering is obviated, which frequentlyoccurswhen the liquid, when fed to the wheel, strikes its bottom, whichcan give rise to harmful deposits on the stationary parts of theatomizer.

In the following, the invention is explained in greater detail withreference to the drawing, in which FIG. 1 is a longitudinalcross-sectional view of the distributor assembly showing the relativepositions of helical ducts with an atomizer wheel and a liquiddistributor in one embodiment of the invention,

FIG. 2 is a partial longitudinal sectional view of the liquiddistributor part of the assembly of FIG. 1,

FIG. 3 is a top view of the distributor part taken along lines 3-3 ofFIG. 2,

FIG. 4 is a longitudinal cross-sectional view of an internal part of theliquid distributor assembly used in combination with the distributorpart of FIG. 2, as shown in FIG. 1,

FIG. 5 is a top view of the internal liquid distributor part taken alongthe line 5-5 of FIG. 4, and

FIG. 6 is a partial side view of the internal part of the liquiddistributor taken along line 6-6 of FIG. 5, showing the configurationsof the helical grooves formed therein.

FIG. 1 shows a part of an atomizer assembly 1 with an atomizer wheel 2mounted on a shaft 3 and having ejection ducts 4.

The liquid or dispersion which is to be fed to the wheel 2, is suppliedvia a conduit 5 surrounding shaft 3 coaxially to a distributor assemblylikewise surrounding the shaft having ducts 6 and consisting of an outerpart 7 and an inner assembly that is divided into two parts 8 and 9.

The parts 7 and 8 are seen in detail in FIGS. 2-5.

It is seen from FIG. 2 that the outer part 7 has an internal,cylindrical surface 10 along a portion of the length. The axialextension of the surface 10 corresponds to the axial length of part 8,which has a corresponding external, cylindrical surface ll. In theexternal, cylindrical surface 11 of part 8, a plurality of helicalgrooves 12 have been machined, the configuration of which is seen ingreater detail in FIG. 6.

When part 8 is mounted in the cylindrical bore in part 7, as can be seenin FIG. 1, the ducts 6 shown in FIG. 1, are produced by means of thehelical grooves 12 in part 8 and the surrounding internal, cylindricalsurface 10 of part 7 which extend helically in the longitudinaldirection.

It will be seen that the very same result can be obtained if part 8 hasan uninterrupted, cylindrical, external surface and if part 7 has acylindrical, internal surface with helically extending grooves formedtherein. It depends entirely upon the considerations taken with respectto production whether one or the other of these designs is chosen, whichconsiderations will have to be taken in each individual case.

The helical ducts 6 terminate in a conical, annular duct 17 formedbetween the external surface of part 9 and the internal, conical surface13 of part 7.

When the liquid is forced downwards through helical ducts 6, a rotatingmotion is imparted to the liquid and it will consequently moverotatingly over the following surface portion of the internal wall ofpart 7, viz. the surface marked with 13 in FIG. 2 and which extendsconically so that its radius diminishes in the direction of flow of theliquid.

Thereby an increased rotational velocity of the liquid is obtained untilthe lowermost edge of the wall portion 13 is reached. The wall continueswith a short section 14 which, in the embodiment shown, is of quiteslight conicity but extends downwardly and is directed outwardly.

This section is so short and its conicity so slight that it has no greatinfluence on the rotational velocity. It has been proven, however, thatwith this shape a better ejection is achieved at the lowermost edge ofthe part. From this edge, the liquid is evenly distributed as a thinfilm that is conical with a vertex angle which may reach as much asl60-l70, or more.

For a given construction, this vertex angle will first and foremostdepend on the pressure at which the liquid is supplied, in that theincreasing rotational speed obtained the increasing pressure renders theejection cone increasingly flatter. At the same time, it followstherefrom that the greater a volume is supplied per unit of time, theflatter the ejection cone becomes. However, it will not be difficultwith a small wheel diameter to ensure that the film of liquid strikesthe wall provided with ducts proper at as low a vertex angle of the coneas 90.

Since it will have to be expected that the liquid, subsequent to havingleft the ducts 6, is essentially present on the inner surfaces of part7, the construction of part 9 is not of decisive importance to thedistribution, but serves primarily to protect the shaft and its bearingsagainst splashes.

With a view to this effect, part 9 extends further forward in front ofthe mouth with its bottom edge 16 than the ejecting edge 15 on part 7.

The inner surface 13 does not necessarily have to be conical as shown inthe drawing, but may possibly be cylindrical or conical with a lowerconicity. Furthermore, it is possible for the conical surface 14 to bereplaced by a cylindrical surface or, possibly, with a surface formingan uninterrupted continuation of surface l3.

What we claim is:

l. A liquid distributor for feeding liquid to a rotating atomizer wheel,said wheel being cup-shaped with a central hub mounted on a verticallypositioned shaft, said shaft being connected with means for rotating thewheel, a number of ejection apertures being provided in the sidewall ofsaid cup-shaped wheel uniformly distributed along the circumferencethereof, the distributor comprising a body mounted coaxially with theatomizer wheel, said body having a plurality of helical ducts thehelical axis of said ducts coinciding with the axis of said atomizerwheel, and terminating in an annular conduit that is coaxial with theatomizer wheel and terminates with an ejecting edge inside said wheel.

2. A liquid distributor as claimed in claim 1, said body comprising atubular portion surrounding said shaft of said wheel and having aninternal, cylindrical surface over a section corresponding to the axialtension of said helical ducts, an annular sleeve being inserted in saidportion, said sleeve being provided with an internal cylindrical surfacefitting closely to said internal cylindrical surface, said helical ductsbeing provided in the shape of helical milled-out tracks in one of saidcylindrical surfaces.

3. A liquid distributor as claimed in claim 1 in which said annularconduit at least on part of its extension is conical and has a diameterdiminishing in the direction towardsthe ejectin edge of said conduit. I

4. A liquid dlstri utor as claimed in claim 3 in which the annularconduit on the last section towards the ejecting edge has a slightopposing conicity.

5. A liquid distributor as claimed in claim 1 in which the mouth oftheannular conduit has an internal limitation projecting further forward indirection of the outflow than the external limitation constituting saidejecting edge.

1. A liquid distributor for feeding liquid to a rotating atomizer wheel,said wheel being cup-shaped with a central hub mounted on a verticallypositioned shaft, said shaft being connected with means for rotating thewheel, a number of ejection apertures being provided in the sidewall ofsaid cup-shaped wheel uniformly distributed along the circumferencethereof, the distributor comprising a body mounted coaxially with theatomizer wheel, said body having a plurality of helical ducts thehelical axis of said ducts coinciding with the axis of said atomizerwheel, and terminating in an annular conduit that is coaxial with theatomizer wheel and terminates with an ejecting edge inside saidwheel.
 1. A liquid distributor for feeding liquid to a rotating atomizerwheel, said wheel being cup-shaped with a central hub mounted on avertically positioned shaft, said shaft being connected with means forrotating the wheel, a number of ejection apertures being provided in thesidewall of said cup-shaped wheel uniformly distributed along thecircumference thereof, the distributor comprising a body mountedcoaxially with the atomizer wheel, said body having a plurality ofhelical ducts the helical axis of said ducts coinciding with the axis ofsaid atomizer wheel, and terminating in an annular conduit that iscoaxial with the atomizer wheel and terminates with an ejecting edgeinside said wheel.
 2. A liquid distributor as claimed in claim 1, saidbody comprising a tubular portion surrounding said shaft of said wheeland having an internal, cylindrical surface over a section correspondingto the axial tension of said helical ducts, an annular sleeve beinginserted in said portion, said sleeve being provided with an internalcylindrical surface fitting closely to said internal cylindricalsurface, said helical ducts being provided in the shape of helicalmilled-out tracks in one of said cylindrical surfaces.
 3. A liquiddistributor as claimed in claim 1 in which said annular conduit at leaston part of its extension is conical and has a diameter diminishing inthe direction towards the ejecting edge of said conduit.
 4. A liquiddistributor as claimed in claim 3 in which the annular conduit on thelast section towards the ejecting edge has a slight opposing conicity.